Hydrogenation desulfurization isomerization catalyst, process for producing the same and method of desulfurization isomerization for sulfurous hydrocarbon oil

ABSTRACT

A process for producing a catalyst for hydrodesulfurization and isomerization of a sulfur-containing hydrocarbon oil, which comprises supporting palladium on a composition comprising a platinum-supported sulfated zirconia and alumina.

TECHNICAL FIELD

The present invention relates to a catalyst for simultaneously achievinghydrodesulfurization and isomerization of a sulfur compound-containinghydrocarbon oil as a target and a process for producing the same. Theinvention also includes a method for hydrodesulfurization andisomerization of a light hydrocarbon oil using the catalyst, which canbe effected with simpler facilities than in conventional techniques andis economically advantageous.

BACKGROUND ART

Isomerization of a light hydrocarbon oil is a technique which hasconventionally been employed extensively in the field of petroleumrefining industry and petrochemical industry. With the trend towardengine performance elevation in motor vehicles and aircraft especiallyin recent years, the gasoline for use as a fuel therein have come to berequired to have a high octane number and hence the isomerization isbecoming important for satisfying the requirement. The so-calledisomerized gasoline has hitherto been used as one of light blend stocksfor gasoline, the isomerized gasoline being obtained by isomerizing alight naphtha that is a light hydrocarbon oil so as to have an improvedoctane number.

Many researches have conventionally been conducted on methods forisomerizing light naphthas, and various catalysts for use in theisomerization reactions are known. Of these, solid acid catalysts can bementioned as the most useful isomerization catalysts. Processes forproducing solid acid catalysts and methods of isomerization using thecatalysts are disclosed, for example, in JP-B-5-29503 and JP-B-6-29199.

However, light naphthas obtained by distillation or cracking of crudeoil, usually contain organosulfur compounds in an amount of about 200 to700 ppm and these organosulfur compounds function as a catalyst poisonfor solid acid catalysts. Therefore, direct isomerization of lightnaphthas has not been a process suitable for industrial use in view ofcatalyst life. In processes which are presently carried out, a two-stagetreatment is conducted, wherein a light naphtha containing sulfurcompounds is treated with a Co—Mo based or Ni—Mo basedhydrodesulfurization catalyst to convert organosulfur compounds intohydrogen sulfide and the hydrogen sulfide is separated from the productoil to thereby prepare a desulfurized light naphtha having a sulfurcontent reduced to several ppm or lower; and thereafter thisdesulfurized light naphtha is used as a feedstock oil to be isomerized.Namely, in the current processes for the isomerization of a lighthydrocarbon oil, the step of hydrodesulfurization is indispensable as apretreatment for the step of isomerization.

If a catalyst for use in the isomerization of a light hydrocarbon oilcan be replaced with a catalyst capable of simultaneously achievinghydrodesulfurization and isomerization, the hydrodesulfurization stepwhich has been indispensable to isomerization processes can be omitted,making it possible to conduct the isomerization more economically withsimpler facilities than in conventional techniques. Specifically, it isdesirable to enable hydrodesulfurization and isomerization reactions tobe conducted simultaneously by loading an isomerization catalyst havingsulfur tolerance into an existing reaction column for the isomerizationof a light hydrocarbon oil and feeding a light hydrocarbon oilcontaining organosulfur compounds as a feedstock oil to be isomerized.

As a catalyst satisfying such a requirement, recently disclosed is acatalyst in which sulfuric acid and a transition metal such as platinumare incorporated into a molded form of zirconia and alumina(WO00/12652). However, the sulfur tolerance thereof is not sufficientlyhigh.

The present inventors have also studied catalysts of sulfated zirconiain combination with a platinum group element. They have found catalystscapable of simultaneously achieving the desulfurization andisomerization of a light hydrocarbon and thus proposed methods forhydrodesulfurization and isomerization using the catalysts(JP-A-2000-233132 and JP-A-2000-234093), but a catalyst having higheractivity and higher sulfur tolerance has been still required.

DISCLOSURE OF THE INVENTION

As a result of the continued studies after the disclosure of the aboveinvention, the present inventors have found that a sulfatedzirconium-alumina catalyst containing a specific platinum on whichpalladium is further supported enables simultaneous hydrodesulfurizationand isomerization of a light hydrocarbon oil containing sulfur compoundsand a process wherein the hydrodesulfurization step prior to theisomerization process is omitted can be employed as a highly practicalprocess.

Specifically, in order to additionally impart hydrodesulfurizing abilityto an isomerization catalyst, useful is a technique of supportingpalladium on a mixture containing a sulfated zirconium and alumina onwhich platinum has been supported. That is, by introducing platinum andpalladium into a catalyst in this order, a catalyst having both ofexcellent hydrodesulfurizing ability and isomerizing ability isobtained. The inventors have further continued to study the catalyst andfound that a catalyst of high activity can be produced by suitablycontrolling the content of platinum and palladium in the catalystproduced by the sequentially supporting technique, and thus, they haveaccomplished the invention.

An object of the invention is to provide, based on the utilization ofthe above new findings obtained by the inventors, a catalyst capable oftreating a hydrocarbon oil having a high sulfur concentration stably fora long period of time as compared with conventional catalysts, in theprocess for producing a catalyst capable of simultaneously achieving thehydrodesulfurization and isomerization of a light hydrocarbon oilcontaining sulfur, and a process for producing the same. Another objectof the invention is to provide a method for hydrodesulfurization andisomerization of a sulfur-containing hydrocarbon oil using the catalyst.

The process for producing a catalyst for hydrodesulfurization andisomerization of a sulfur-containing hydrocarbon oil according to theinvention comprises supporting palladium on a mixture comprising aplatinum-supported sulfated zirconia and alumina. Specific illustrationthereof with reference to operations is the production process whichcomprises the following steps:

(1) an alumina-mixing step of mixing a platinum-supported sulfatedzirconium hydroxide and pseudoboehmite;

(2) a molding step of molding the resulting mixture into a catalystform;

(3) a calcining step of calcining the molded form to stabilize it; and

(4) a palladium-supporting step of supporting palladium.

The catalyst for desulfurization and isomerization of asulfur-containing hydrocarbon oil according to the invention is acatalyst which is produced by the above process and which has a platinumcontent of 0.05 to 5% by weight, a palladium content of 0.05 to 10% byweight, and a specific surface area of 50 to 200 m²/g.

The method for hydrodesulfurization and isomerization of asulfur-containing hydrocarbon oil according to the invention using thecatalyst comprises bringing a light hydrocarbon oil having a sulfurcontent of 700 ppm by weight or lower and hydrogen into contact with theabove catalyst under reaction conditions: a temperature of 160 to 300°C., a pressure of 1.0 to 10.0 MPa, an LHSV of 0.1 to 10 h⁻¹, and ahydrogen/oil ratio of 100 to 1,000 NL/L to achieve isomerization anddesulfurization simultaneously.

BEST MODE FOR CARRYING OUT THE INVENTION

The following will explain the invention in detail.

[Sulfated Zirconium Hydroxide]

The zirconium hydroxide to be used in the invention is a hydroxide or apartially oxidized hydroxide of zirconium. Zirconium hydroxides andpartially oxidized zirconium hydroxides exist in forms includingZr(OH)₄, Zr(OH)₂, Zr(OH)₃ and ZrO(OH)₂, and any of these can be used.Preferred are Zr(OH)₄ and ZrO(OH)₂. These hydroxides or partiallyoxidized hydroxides of zirconium may be hydrates.

The hydroxide or partially oxidized hydroxide of zirconium is sulfatedto prepare a sulfate group-containing zirconium hydroxide. Examples of atreating agent which gives a sulfate group include sulfuric acid,ammonium sulfate, sulfurous acid, ammonium sulfite, hydrogen sulfide,sulfurous acid gas, and the like. Preferred are Sulfuric acid andammonium sulfate. Any methods can be used for the sulfation.

Examples thereof include an adsorption method, an impregnation method,and a mixing method. With regard to the sulfation method, there is nospecial limitation in a method of dissolving the treating agent,solvent, treating period, and temperature, and they can be suitablyselected within the range in which the advantages of the invention areobtained.

[Platinum]

In the process for producing the catalyst of the invention, the othermetal may be present at the time when platinum is supported on thesulfated zirconium hydroxide unless the advantages of the invention isinhibited. The other metal may be palladium, ruthenium, iridium, nickel,cobalt and the like, and two or more of these metals may beincorporated. Techniques for supporting platinum is not particularlylimited but an impregnation method and an ion-exchange method well-knownto persons skilled in the art are representative methods therefor. Anymethods may be adopted as far as they can support platinum on a sulfategroup-supported zirconium hydroxide highly dispersively andhomogeneously.

The platinum compound for use in the supporting of platinum may be anyof various water soluble salts, such as chloride, bromide, iodide,sulfate, nitrate, and ammine complex salts. The supporting of platinummay be conducted not only after the aforementioned sulfation of theabove zirconium hydroxide but also before the treatment or at the sametime. The performance of the final catalysts are about the same evenwhen they are supported in any order.

The content of platinum is, as a ratio in the catalyst finally obtained,is 0.05 to 5% by weight, preferably 0.1 to 3% by weight.

For obtaining an effect as a solid acid catalyst, the content of 0.05%by weight or more is preferred. The content of 5% by weight or less ispreferred because dispersibility of the active metals is maintained andactivity of the solid acid catalyst is obtained.

[Mixing with alumina]

As the alumina for use in the invention, various forms of aluminumhydroxides or hydrated aluminum hydroxides, such as pseudoboehmite,γ-alumina, η-alumina and α-alumina, can be used, but for obtaining apractical crush strength as a catalyst, the use of pseudoboehmite ispreferred. In general, an alumina having a pseudoboehmite structure isavailable in a powder form or in a sol form which is a dispersion in aliquid.

In the invention, when pseudoboehmite is used as the alumina, thefollowing method of the use is suitable, for example. Namely, afterpseudoboehmite has been added to and mixed with the platinum-supportedsulfated zirconium hydroxide, a medium for molding is added and thewhole is further mixed and then molded to obtain a molded form forcatalyst. At that time, as far as a practical crush strength as acatalyst is obtained, an alumina having the other crystalline form canbe added in addition to pseudoboehmite. As far as the advantage of thecatalyst of the invention is obtained, the other metal oxide may be, ofcourse, added.

For the mixing of the platinum-supported sulfated zirconium hydroxidewith pseudoboehmite, a kneader generally employed for catalystproduction can be used, but any mixing means may be used as far as crushstrength as a catalyst on a practical level is obtained.

As a medium to be added after the addition and mixing of theplatinum-supported sulfated zirconium hydroxide with pseudoboehmite,various solvents can be used alone or as a mixture of two or morethereof, the solvents including alcoholic organic solvents such asmethanol and ethanol, acidic solvents such as sulfuric acid, dilutesulfuric acid, nitric acid, hydrochloric acid, and acetic acid, and thelike. The most easily available and also preferable in use is water.

Alternatively, a molded form of the sulfated zirconium hydroxidecontaining platinum can be obtained by mixing the sulfated zirconiumhydroxide with pseudoboehmite and then adding an aqueous solutioncontaining platinum thereto, followed by mixing and molding.

The ratio of the platinum-supported sulfated zirconium hydroxide to thealumina (zirconium oxide/alumina) is preferably in the range of 97/3 to60/40 (unit: % by weight), preferably 95/5 to 80/20 in terms of theratio in the solid acid catalyst finally obtained.

Since an alumina plays a role as a binder, the amount of 3% by weight ormore is preferred because a binding power of the catalyst becomesstrong. On the other hand, the amount of the alumina of 40% by weight orless is preferred because crush strength of the catalyst is obtained anda relative amount of the sulfated zirconium hydroxide can be maintainedto secure a necessary solid acid amount.

[Molding and Calcination of Platinum-Supported Sulfated Zirconia-AluminaComposition]

The mixture of the platinum-supported sulfated zirconium hydroxide andalumina obtained as above is subsequently molded into a catalystprecursor form having a suitable form as a catalyst by a technique knownto persons skilled in the art. Examples of the technique include anextrusion molding method, a rolling granulation method, adropping-into-oil method, and the like. The extrusion molding method ispreferred.

The molded form is not particularly limited in size, but usually themixture is molded into a size having a diameter of the catalystcross-section of 1 to 5 mm. Especially when an extrusion-molded producthaving a cylindrical, four-cusped or similar shape is to be produced, itis easy to obtain a catalyst having a length of about 1 to 20 mm, whichis practically advantageous.

The molded catalyst precursor form is dried and further subjected tocalcination for stabilization. The calcination is conducted by heatingthe precursor form under an oxidizing atmosphere at a temperature in therange of 200 to 800° C., preferably 250 to 750° C., over a period of 0.5to 10 hours.

The calcining temperature of the lower limit, i.e., 200° C., or higheris preferred because the crush strength is high when the molded form isconverted into a catalyst. On the other hand, the temperature of theupper limit, i.e., 800° C., or lower is preferred because the sulfategroups incorporated are prevented from volatilizing and a catalysthaving solid acidity is obtained.

The calcined molded form is dehydrated completely or incompletely to beconverted into a zirconium oxide or a partially oxidized zirconiumhydroxide, but as far as the calcination is conducted within the rangeof 200° C. to 800° C., the oxide or hydroxide in any form may besuitable.

[Supporting of Palladium]

The supporting of palladium on the platinum-supported sulfatedzirconia-alumina thus obtained can be conducted by general methods suchas an impregnation method, an ion-exchange method, or an adsorptionmethod. Any method can be adopted as far as it can support palladium onthe molded form highly dispersively and homogeneously.

As a salt which is a palladium supplying source, use can be made of ahydrochloride such as palladium chloride PdCl₂, palladium ammoniumtetrachloride (NH₄)₂PdCl₄, or palladium ammonium hexachloride(NH₄)₂PdCl₆; an acetate such as palladium acetate Pd(CH₃COO)₂; a sulfatesuch as palladium sulfate PdSO₄, PdSO₄.nH₂O; a nitrate such as palladiumnitrate Pd(NO₃)₂; a palladium salt such as tetraammine dichloropalladiumPd(NH₃)₄Cl₂ nH₂O. Preferred is a hydrochloride, sulfate, nitrate,acetate, or the like salt of palladium and most preferred is a palladiumhydrochloride.

The supported amount of palladium is preferably 0.05 to 10% by weight,more preferably 0.1 to 5% by weight in terms of the ratio in the solidacid catalyst finally obtained.

The amount of 0.05% by weight or more is preferred because the value ofadding palladium as a solid acid catalyst, i.e., the purpose ofrealizing both of sulfur tolerance and isomerization activity can beachieved. The amount of 5% by weight or less is preferred becausedispersibility of palladium is maintained and catalyst activity isobtained.

[Calcination after Supporting of Palladium]

The palladium-supported product of the platinum-supported sulfatedzirconia-alumina is dried and then calcined to thereby obtain a finalcatalyst. The calcination is conducted by heating the product under anoxidizing atmosphere at a temperature in the range of 100 to 800° C.,preferably from 120 to 750° C., over a period of 0.5 to 10 hours.

The calcination temperature of 100° C. or higher is preferred becausewater can be evaporated and hence affinity between palladium and themolded form becomes strong, whereby effusion of palladium is inhibited.The calcination temperature of 800° C. or lower is preferred because thesupported palladium does not aggregate, its highly dispersed state ismaintained, and as a result, a catalyst of high activity is obtained.

[Composition of Final Catalyst]

The content of the sulfate group in the catalyst produced according tothe process for producing the catalyst of the invention varies dependingon treating conditions such as the kind of the sulfation-treating agent,its concentration, and processing history, especially temperature andperiod of heating, but it is desirable to be in the range of 0.1 to 5%by weight, preferably 0.5 to 4% by weight in terms of sulfur.

The sulfur content of 0.1% by weight or more is preferred because thecatalyst has sufficient acidity and functions as a solid acid catalystand hence catalyst activity is enough. The content of 5% by weight orless is preferred because the sulfate group can be prevented fromexcessively covering the zirconia surface and accumulating on thesurface to deactivate active sites and hence catalyst activity isenough.

The sulfur content in the catalyst is measured by burning a sample in anoxygen stream to oxidize the sulfur contained in the sample to convertit into sulfurous acid gas (SO₂), removing water and dust, and thendetecting the amount of SO₂ with an infrared detector, e.g., asolid-state detector. According to this analytical method, the sulfurcontent in a sample can be determined in the concentration range of0.001 to 99.99%.

The catalyst of the invention preferably has a specific surface area inthe range of 50 to 200 m²/g, preferably 60 to 160 m²/g.

When the specific surface area is 50 m²/g or larger, the active metalsare present in a highly dispersed state to give a larger area of contactwith reactants, and hence the catalyst can be utilized as a solid acidcatalyst. On the other hand, the specific surface area of 200 m²/g orsmaller is preferred because the catalyst has solid acidity and crushstrength as a catalyst can be maintained.

The specific surface area of the catalyst can be calculated by measuringan adsorbed amount according to the nitrogen adsorption method using ameasuring apparatus known to persons skilled in the art.

The catalyst of the invention preferably has a crush strength of 0.2 to5.0 kg/2 mm, more preferably 0.3 to 3.0 kg/2 mm.

The crush strength of 0.2 kg/2 mm or higher is preferred because thecatalyst can be prevented from being destroyed by its own weight whenpacked into a practical apparatus. The crush strength of 5.0 kg/2 mm orlower is preferred because a catalyst can be obtained which generallyhas a large specific surface area and a sufficiently large number ofactive sites necessary for reactions and which, as a result, has highactivity.

By following the aforementioned process for production, i.e., byconducting the procedure of first preparing a platinum-supportedsulfated zirconia-alumina and then supporting palladium, a catalystcapable of achieving desulfurization and isomerization simultaneously isobtained. The reason for this fact is not clear but the following ispresumed.

That is, a platinum-supported sulfated zirconia has isomerizationactivity but, because it alone does not have desulfurizing ability, itcannot achieve isomerization and desulfurization for a long period andis deactivated within a short period when brought into contact with asulfur-containing hydrocarbon.

On the other hand, in the catalyst obtained by first preparing aplatinum-supported sulfated zirconia-alumina and then supportingpalladium, palladium is located on the alumina surface and thepalladium-alumina acts as a new desulfurization site. It is consideredthat the reason why the catalyst of the invention exhibits the abilityof isomerization and desulfurization for a long period is that suchrole-sharing is attained.

The positions of these metals can be observed by an X-ray micro analyzer(EPMA: Electron Probe Micro Analyzer). Based on the observation, atendency can be confirmed that platinum is located on zirconia andpalladium is located on alumina, respectively.

[Method for Hydrodesulfurization and Isomerization]

A light hydrocarbon oil containing organosulfur compounds, such as astraight-run light naphtha taken through atmospheric distillationapparatus of a crude-oil, a light naphtha separated from a whole naphthalikewise taken through atmospheric distillation apparatus of acrude-oil, or a Merox naphtha obtained by subjecting a light naphtha tothe Merox treatment, is suitable as the feedstock oil to be desulfurizedand simultaneously isomerized using the catalyst of the invention.

An especially suitable feedstock oil is a light naphtha having an ASTMdistillation temperature of 25 to 130° C., preferably 25 to 110° C.

With respect to the content of organosulfur compounds, a light naphthahaving an organosulfur content of 700 ppm by weight or lower, preferablyabout 10 to 500 ppm by weight, more preferably about 10 to 200 ppm byweight, can be suitably used. It is a matter of course that a lighthydrocarbon oil having a sulfur content of less than 10 ppm can also beused as the feedstock oil.

[Examples of Organosulfur Compounds]

Representative examples of the organosulfur compounds contained in lightnaphthas include thiol compounds, R—SH, such as 2-propanethiol,(CH₃)₂CH—SH, and ethanethiol, C₂H₅—SH, sulfide compounds, R—S—R, such asmethyl ethyl sulfide, CH₃—S—C₂H₅, disulfide compounds, R—SS—R, such asethyl isopropyl disulfide, C₂H₅—SS—CH(CH₃)₂, and the like. Using thecatalyst of the invention, these sulfur compounds can be removedsimultaneously with the isomerization of the light hydrocarbon oil.

[Components in the Feedstock Oil]

From the standpoint of maintaining the catalytic activity over a longerperiod, it is preferred that the amounts of aromatics, unsaturatedhydrocarbons, and higher hydrocarbons in the light naphtha to be treatedbe small. The amount of benzene is preferably 5% by volume or smaller,more preferably 3% by volume or smaller. The amount of naphthenes ispreferably 12% by volume or smaller, more preferably 9% by volume orsmaller. That of C₇ compounds is preferably 15% by volume or smaller,more preferably 10% by volume or smaller.

[Reaction Conditions for Hydrodesulfurization and Isomerization]

Conditions for the hydrodesulfurization and isomerization using thecatalyst of the invention are as follows:

-   Reaction temperature: 160 to 300° C., preferably 180 to 250° C.-   Reaction pressure: 1.0 to 10.0 MPa, preferably 1.4 to 4.5 MPa-   LHSV: 0.1 to 10 h⁻¹, preferably 0.5 to 5 h⁻¹-   Hydrogen/oil ratio: 100 to 1,000 NL/L, preferably 150 to 800 NL/L

The reaction temperature of 160° C. or higher is preferred becausecatalyst life is prolonged. On the other hand, the temperature of 300°C. or lower is preferred because the feedstock oil is prevented fromdecomposition and the yield of the product oil does not decrease.

The other conditions, i.e., reaction pressure, LHSV, and hydrogen/oilratio, are almost the same as the conditions for the isomerization oflight hydrocarbon oils, which have been conducted hitherto.

The catalyst of the invention can be used in place of isomerizationcatalysts heretofore in use, whereby not isomerization alone buthydrodesulfurization and isomerization can be simultaneously conducted.Namely, the organosulfur compounds contained in the feedstock oil can behydrodesulfurized into hydrogen sulfide to reduce the sulfur content toseveral ppm or lower and, simultaneously therewith, a component having alow octane number can be isomerized into a component having a highoctane number. Thus, a product oil containing substantially no sulfurcompound and having an improved octane number can be obtained.

EXAMPLES

The following will describe the invention in more detail with referenceto Examples, but the invention should not be construed as being limitedto these Examples unless it exceeds the gist of the invention.

Example 1 Production of Catalyst “A”

(1) Preparation of Sulfated Zirconium Hydroxide

To 4,000 g of 1N sulfuric acid was added 400 g of a zirconium hydroxide(Zr(OH)₄), followed by stirring for 30 minutes. Thereafter, the mixturewas filtered and the resulting solid material was dried at 110° C. for awhole day and night to obtain 452 g of a sulfated zirconium hydroxidecontaining a sulfate group.

(2) Supporting of Platinum on Sulfated Zirconium Hydroxide

To an aqueous solution of 2.7 g of chloroplatinic acid dissolved thereinwas added 375 g of the above sulfated zirconium hydroxide, wherebyimpregnation with the Pt salt was effected. Thereafter, drying at 110°C. for a whole day and night afforded 377 g of a platinum-supportedsulfated zirconium hydroxide.

(3) Molding of Catalyst

After 377 g of the platinum-supported sulfated zirconium hydroxide wasthoroughly mixed with 68.7 g of commercially available pseudoboehmite(manufactured by Catalysts & Chemicals Ind. Co., Ltd.), 200 g of waterwas added thereto, followed by kneading. The kneaded mixture wasextruded through a molding machine at a diameter of 1.8 mm. The extrudedkneaded product was dried at 110° C. for 2 hours to obtain 446 g of aprecursor of a molded form.

(4) Stabilization of Molded Form

The precursor of a molded form was calcined in a muffle furnace at 600°C. for 3 hours to obtain 354 g of a stabilized molded form.

(5) Supporting of Palladium on Molded Form

With 120 g of an aqueous solution containing 2.9 g of palladium chloridedissolved therein was impregnated 354 g of the molded form for 30minutes. Thereafter, the impregnated molded form was dried under anitrogen stream and then calcined at 450° C. for 3 hours to obtain 355 gof a catalyst “A” as a final product.

Example 2 Production of Catalyst “B”

A production process was conducted in the same manner as in Example 1with the exception that a mixed aqueous solution of 2.7 g ofchloroplatinic acid and 0.5 g of palladium chloride was used instead ofthe aqueous solution containing 2.7 g of chloroplatinic acid dissolvedtherein in the step of (2) Supporting of platinum on sulfated zirconiumhydroxide in Example 1, whereby 355 g of a catalyst “B” was obtained.

Example 3 Production of Catalyst “C”

A production process was conducted in the same manner as in Example 1with the exception that an aqueous solution containing 13.3 g ofchloroplatinic acid dissolved therein was used instead of the aqueoussolution containing 2.7 g of chloroplatinic acid dissolved therein inthe step of (2) Supporting of platinum on sulfated zirconium hydroxidein Example 1 and 1.2 g of palladium chloride was used instead of 2.9 gof palladium chloride in the step of (5) Supporting of palladium,whereby 363 g of a catalyst “C” was obtained.

Example 4 Production of Catalyst “D”

A production process was conducted in the same manner as in Example 1with the exception that an aqueous solution containing 1.8 g ofchloroplatinic acid dissolved therein was used instead of the aqueoussolution containing 2.7 g of chloroplatinic acid dissolved therein inthe step of (2) Supporting of platinum on sulfated zirconium hydroxidein Example 1 and 14.7 g of palladium chloride was used instead of 2.9 gof palladium chloride in the step of (5) Supporting of palladium,whereby 364 g of a catalyst “D” was obtained.

Example 5 Production of Catalyst “E”

A production process was conducted in the same manner as in Example 1with the exception that an aqueous solution containing 22.1 g ofchloroplatinic acid dissolved therein was used instead of the aqueoussolution containing 2.7 g of chloroplatinic acid dissolved therein inthe step of (2) Supporting of platinum on sulfated zirconium hydroxidein Example 1 and 0.6 g of palladium chloride was used instead of 2.9 gof palladium chloride in the step of (5) Supporting of palladium,whereby 370 g of a catalyst “E” was obtained.

Example 6 Production of Catalyst “F”

A production process was conducted in the same manner as in Example 1with the exception that an aqueous solution containing 0.9 g ofchloroplatinic acid dissolved therein was used instead of the aqueoussolution containing 2.7 g of chloroplatinic acid dissolved therein inthe step of (2) Supporting of platinum on sulfated zirconium hydroxidein Example 1, 26.4 g of palladium chloride was used instead of 2.9 g ofpalladium chloride in the step of (5) Supporting of palladium, and thecalcination was conducted at 550° C., whereby 375 g of a catalyst “F”was obtained.

Comparative Example 1 Production of Catalyst “G”

(1) Preparation of Sulfated Zirconium Hydroxide

To 4,000 g of 1N sulfuric acid was added 400 g of a zirconium hydroxide(Zr(OH)₄), followed by stirring for 30 minutes. After the stirring, themixture was filtered and the resulting solid material was dried at 110°C. for a whole day and night to obtain 452 g of a sulfated zirconiumhydroxide.

(2) Supporting of Platinum on Sulfated Zirconium Hydroxide

To an aqueous solution containing 2.7 g of chloroplatinic acid dissolvedtherein was added 375 g of the sulfated zirconium hydroxide, wherebyimpregnation with the Pt salt was effected. Thereafter, drying at 110°C. for a whole day and night afforded 377 g of a platinum-supportedsulfated zirconium hydroxide.

(3) Molding of Catalyst

After 377 g of the platinum-supported sulfated zirconium hydroxide wasthoroughly mixed with 68.7 g of commercially available pseudoboehmite(manufactured by Catalysts & Chemicals Ind. Co., Ltd.), 200 g of waterwas added thereto, followed by kneading. The kneaded mixture wasextruded through a die having a diameter of 1.8 mm. The extruded productwas dried at 110° C. for 2 hours to obtain 446 g of a precursor of amolded form.

(4) Stabilization of Molded Form

The molded form was calcined in a muffle furnace at 600° C. for 3 hoursto obtain 354 g of a catalyst “G”.

Comparative Example 2 Production of Catalyst “H”

(1) Preparation of Sulfated Zirconium Hydroxide

To 4,000 g of 1N sulfuric acid was added 400 g of a zirconium hydroxide(Zr(OH)₄), followed by stirring for 30 minutes. After the stirring, themixture was filtered and the resulting solid material was dried at 110°C. for a whole day and night to obtain 452 g of a sulfated zirconiumhydroxide.

(2) Molding of Catalyst

After 375 g of the sulfated zirconium hydroxide was thoroughly mixedwith 68.7 g of commercially available pseudoboehmite (manufactured byCatalysts & Chemicals Ind. Co., Ltd.), 200 g of water was added thereto,followed by kneading. The kneaded mixture was extruded through a moldingmachine at a diameter of 1.8 mm and the product was dried at 110° C. for2 hours to obtain 444 g of a precursor of a molded form.

(3) Stabilization of Molded Form

The molded form was calcined in a muffle furnace at 600° C. for 3 hoursto obtain 352 g of a molded form.

(4) Supporting of Palladium

With 120 g of an aqueous solution containing 2.9 g of palladium chloridedissolved therein was impregnated 354 g of the molded form for 30minutes. Thereafter, the impregnated molded form was dried under anitrogen stream and then calcined at 450° C. for 3 hours to obtain 353 gof a catalyst “H”.

Comparative Example 3 Production of Catalyst “I”

(1) Preparation of Sulfated Zirconium Hydroxide

To 4,000 g of 1N sulfuric acid was added 400 g of a zirconium hydroxide(Zr(OH)₄), followed by stirring for 30 minutes. After the stirring, themixture was filtered and the resulting solid material was dried at 110°C. for a whole day and night to obtain 452 g of a sulfated zirconiumhydroxide.

(2) Preparation of Palladium-Supported Sulfated Zirconium Hydroxide

To an aqueous solution resulting 2.9 g of palladium chloride dissolvedtherein was added 375 g of the sulfated zirconium hydroxide, wherebyimpregnation with the Pd salt was effected. Thereafter, drying at 110°C. for a whole day and night afforded 376 g of a palladium-supportedsulfated zirconium hydroxide.

(3) Molding of Catalyst

After 376 g of the palladium-supported sulfated zirconium hydroxide wasthoroughly mixed with 68.7 g of commercially available pseudoboehmite(manufactured by Catalysts & Chemicals Ind. Co., Ltd.), 200 g of waterwas added thereto, followed by kneading. The kneaded mixture wasextruded through a molding machine at a diameter of 1.8 mm. The extrudedproduct was dried at 110° C. for 2 hours to obtain 445 g of a precursorof a molded form.

(4) Stabilization of Molded Form

The precursor of a molded form was calcined in a muffle furnace at 600°C. for 3 hours to obtain 352 g of a molded form.

(5) Supporting of Platinum

With 120 g of an aqueous solution containing 2.7 g of chloroplatinicacid dissolved therein was impregnated 352 g of the molded form for 30minutes. Thereafter, the impregnated molded form was dried under anitrogen stream and then calcined at 450° C. for 3 hours to obtain 354 gof a catalyst “I” as a final product.

Comparative Example 4 Production of Catalyst “J”

(1) Preparation of Sulfated Zirconium Hydroxide

To 4,000 g of 1N sulfuric acid was added 400 g of a zirconium hydroxide(Zr(OH)₄), followed by stirring for 30 minutes. After the stirring, themixture was filtered and the resulting solid material was dried at 110°C. for a whole day and night to obtain 452 g of a sulfated zirconiumhydroxide.

(2) Preparation of Palladium-Platinum-Supported Sulfated ZirconiumHydroxide

To an aqueous solution containing 2.7 g of chloroplatinic acid and 2.9 gof palladium chloride dissolved therein was added 375 g of the sulfatedzirconium hydroxide, whereby impregnation with the Pt salt and the Pdsalt was effected. Thereafter, drying was effected at 110° C. for awhole day and night to obtain 378 g of a palladium-platinum-supportedsulfated zirconium hydroxide.

(3) Molding of Catalyst

After 378 g of the palladium-platinum-supported sulfated zirconiumhydroxide was thoroughly mixed with 68.7 g of commercially availablepseudoboehmite (manufactured by Catalysts & Chemicals Ind. Co., Ltd.),200 g of water was added thereto, followed by kneading. The kneadedmixture was extruded through a molding machine at a diameter of 1.8 mmand the extruded product was dried at 110° C. for 2 hours to obtain 447g of a precursor of a molded form.

(4) Stabilization of Molded Form

The molded form was calcined in a muffle furnace at 600° C. for 3 hoursto obtain 355 g of a catalyst “J”.

Comparative Example 5 Production of Catalyst “K”

A process was conducted in the same manner as in Comparative Example 2with the exception that the aqueous solution of 2.9 g of palladiumchloride was replaced by a mixed aqueous solution of 2.9 g of palladiumchloride and 2.7 g of chloroplatinic acid in the step of (4) Supportingof palladium in Comparative Example 2, whereby 354 g of a catalyst “K”was obtained.

Comparative Example 6 Production of Catalyst “L”

A production process was conducted in the same manner as in Example 1with the exception that a temperature of 900° C. was adopted instead ofthe calcination temperature of 600° C. in the step of (5) Supporting ofpalladium in Example 1, whereby 348 g of a catalyst “L” was obtained.

The production conditions and physicochemical properties of the abovecatalysts A to F (Examples) and G to L (Comparative Examples) aresummarized in Table 1 (Examples) and Table 2 (Comparative Examples).Each measuring apparatus used is as follows.

-   [Specific surface area and pore volume] a high-precision automatic    gas adsorption apparatus “BELSORP 28”, manufactured by BEL JAPAN,    INC.-   [Sulfur content] a sulfur content analyzer “SC-132”, manufactured by    LECO Co., Ltd.-   [Crush strength of catalyst] a Kiya type hardness meter manufactured    by Kiya Seisakusho. Twenty cylindrically molded catalyst samples    having a length of about 2 mm were selected and the strength of the    catalyst in the transverse direction was measured. The average value    was taken as crush strength (kg/2 mm).

TABLE 1 Examples Example 1 2 3 4 5 6 Catalyst A B C D E F Pt content 0.30.4 1.5 0.2 2.5 0.1 (% by weight) Pd content 0.5 0.5 0.2 2.5 0.1 4.5 (%by weight) Specific 135 125 101 62 73 155 surface area (m²/g) Porevolume 0.20 0.21 0.23 0.27 0.23 0.15 (cc/g) Sulfur content 2.8 2.5 3.00.7 1.2 3.5 (% by weight) Crush strength 1.8 2.0 1.9 2.6 1.8 1.3 (kg/2mm)

TABLE 2 Comparative Examples Comparative Example 1 2 3 4 5 6 Catalyst GH I J K L Pt content 0.3 0.0 0.3 0.3 0.3 0.3 (% by weight) Pd content0.0 0.5 0.5 0.5 0.5 0.5 (% by weight) Specific 137 130 135 132 128 50surface area (m²/g) Pore volume 0.20 0.20 0.20 0.21 0.20 0.30 (cc/g)Sulfur content 2.8 2.7 2.5 2.2 2.7 0.5 (% by weight) Crush strength 1.92.0 1.7 2.0 1.6 3.1 (kg/2 mm)[Use Examples of Catalyst]

Each catalyst was packed into a fixed-bed flow-through type reactorhaving a catalyst packing capacity of 7 ml. A straight-run light naphthataken from an atmospheric distillation apparatus was fed thereto as afeedstock hydrocarbon oil. The straight-run light naphtha had a sulfurcontent of 490 ppm by weight. The feedstock oil was fed under thefollowing conditions to conduct isomerization.

-   Reaction temperature: 200° C.-   Hydrogen pressure in reaction: 3.0 MPa-   LHSV: 1.5/h⁻¹-   Hydrogen/oil ratio: 350 NL/L

The composition of the oil taken at the outlet of the reactor at 20hours and 150 hours after the start of oil feeding was analyzed by gaschromatography and the sulfur content after 150 hours was measured onthe sulfur analyzer. The results are shown in Table 3 (Examples) andTable 4 (Comparative Examples).

TABLE 3 S content (ppm by C₅ isomer ratio (%) weight) 20 hours 150 hours150 hours Catalyst A 70 70 0 (Example 1) Catalyst B 69 68 1 (Example 2)Catalyst C 71 69 1 (Example 3) Catalyst D 66 65 0 (Example 4) Catalyst E65 64 1 (Example 5) Catalyst F 65 66 2 (Example 6)

TABLE 4 S content (ppm by C₅ isomer ratio (%) weight) 20 hours 150 hours150 hours Catalyst G 71 43 490 (Comparative Example 1) Catalyst H 68 554 (Comparative Example 2) Catalyst I 65 47 5 (Comparative Example 3)Catalyst J 66 60 3 (Comparative Example 4) Catalyst K 67 58 3(Comparative Example 5) Catalyst L 47 45 9 (Comparative Example 6)C₅ isomer ratio (%)=[Content (% by weight) of iso-C₅ component inproduct oil/Content (% by weight) of all C₅ components in productoil]×100

The data given in the above show that when the catalysts producedaccording to the process of the invention, i.e., the catalysts A to F ofExamples 1 to 6, are used to conduct isomerization, which is arepresentative reaction for solid acid catalysts, the C₅ isomer ratio inthe product oil is maintained at 64% or higher even after 150 hours andthus these catalysts are excellent solid acid catalysts. At the sametime, the sulfur content in the product oil is 1 ppm or lower, and thisfact shows that isomerization and desulfurization are achievedsimultaneously.

In Comparative Example 1 in which palladium was not supported, the C₅isomer ratio after 20 hours is a high value of 71% but it drops to 43%after 150 hours. In this example, the sulfur content in the product oilis high, and this fact shows that desulfurization does not proceed. Evenwhen palladium is incorporated, with the catalysts which are notproduced according to the process of the invention (Comparative Examples2, 3, 4, and 5), high C₅ isomer ratios are obtained at 20 hours afterthe start of the reaction, but the activity drops after 150 hours andthe C₅ isomer ratios decrease to 60% or lower.

Industrial Applicability

The catalysts produced by the processes according to the invention candirectly isomerize a straight-run naphtha produced from an atmosphericdistillation apparatus although sulfur compounds are present therein inhigh concentration and also can simultaneously achievehydrodesulfurization. Thus, a process in which the desulfurizationpretreatment of a light naphtha, which has been indispensable toconventional isomerization of a light naphtha, is omitted can be carriedout industrially advantageously.

1. A process for producing a hydrodesulfurization and isomerizationcatalyst for a sulfur-containing hydrocarbon oil, which comprisessupporting palladium on a composition comprising a platinum-supportedsulfated zirconia and alumina, which comprises conducting the following(1)-(5) in the recited order: (1) an alumina-mixing step of mixing aplatinum-supported sulfated zirconium hydroxide and pseudoboehmite; (2)a molding step of molding the resulting mixture into a catalyst moldedform; (3) a calcining step in which the molded form is calcined at atemperature of 200° C. to 800° C. for a period of 0.5 to 10 hours in anoxidizing atmosphere to stabilize it; (4) a palladium-supporting step ofsupporting palladium on the calcined molded form; and (5) a calciningstep of the palladium-supported product in which the palladium-supportedproduct is calcined at a temperature of 100° C. to 800° C. for a periodof 0.5 to 10 hours in an oxidizing atmosphere to produce a finalcatalyst.
 2. The process for producing a hydrodesulfurization andisomerization catalyst for a sulfur-containing hydrocarbon oil accordingto claim 1, wherein the final catalyst has a platinum content of 0.05 to1.5% by weight and a palladium content of 0.05 to 0.5% by weight.